Theroux's representative confirmed the news of his engagement to the 43-year-old former Friends star, reported People magazine.
'Justin Theroux had an amazing birthday on Friday, receiving
an extraordinary gift when his girlfriend, Jennifer Aniston, accepted his proposal of marriage,' the representative said in a statement.
Aniston and Theroux have been dating for more than a year.
Days before the engagement, the pair was spotted vacationing in Kauai, Hawaii.
This will be a second marriage for her but the first for Theroux.
She was previously married to actor Brad Pitt, who is now engaged to Angelina Jolie.
Photograph: Kevin Winter/Getty Images